The Effect of High-flow Nasal Oxygen Flow Rate on Gas Exchange During Apnoea (Apox-HFNO)

A Randomised Controlled Trial of Apnoeic Oxygenation With No-flow vs High-flow vs Ultra High-flow Nasal Oxygen

Apnoeic oxygenation refers to oxygenation that occurs through the insufflation of oxygen into the lungs in the absence spontaneous respiration or positive pressure ventilation. It is used to extend the time to desaturation at induction of anaesthesia and as a primary oxygenation technique during airway surgery. The impact of high-flow nasal oxygen flow rate selection on gas exchange is poorly understood. Participants in this study will be randomised to receive a certain nasal oxygen flow rate during apnoea and its effect on gas exchange will be measured by blood gas analysis.

Study Overview

• Status: Completed
• Conditions: Apnea; Anesthesia; Respiration; Arrest
• Intervention / Treatment: Procedure: Apnoeic oxygenation

Detailed Description

Apnoeic oxygenation with high-flow nasal oxygen has been proposed to result in carbon dioxide clearance. However, this has been poorly quantified.

This study will compare use of nasal oxygen at different flow rates during apnoea with that of a control that does not receive nasal oxygen. Participants are anaesthetised after standardised pre-oxygenation with high-flow nasal oxygen, after which they will receive one of three nasal oxygen flow rates (0, 70, 120 L/min).

The rate of carbon dioxide elevation will be measured by arterial blood gas analysis after the onset of apnoea and compared between the three groups to discern the relative rates of carbon dioxide clearance after the first minute of apnoea. The effect of nasal oxygen flow rate on oxygenation will also be measured.

• Study Type: Interventional
• Enrollment (Actual): 114
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Ireland
  • Galway, Ireland
    • University Hospital Galway

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• 18 years of age or older
• ASA 1 or 2
• Receiving a general anaesthetic for non-emergent surgery

Exclusion Criteria:

• ASA score ≥3
• BMI ≥ 30 kg/m2
• Nasal obstruction
• Baseline SpO2 ≤95% on room air
• Anticipated difficult airway management
• Requirement for awake intubation
• Pregnancy
• Positive PCR test for coronavirus in preceding 14 days.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: Apnoea without apnoeic oxygenation; High-flow nasal oxygen administration ceases at the onset of apnoea.	Procedure: Apnoeic oxygenation; After 2mins 45 seconds of pre-oxygenation with high-flow nasal oxygen at Fio2 1.0 at 50L/min, anaesthesia is induced with 1-1.5mcg/kg remifentanil plus 2-3mg/kg propofol. Propofol (10mg/kg/hr) and remifentanil (0.15mcg/kg/min) infusions administered until study conclusion. At the onset of apnoea, 1mg/kg rocuronium administered. Jaw thrust performed. High-flow nasal oxygen adjusted to the randomised flow rate. Videolaryngoscopy after 1 minute of apnoea. Airway patency maintained. Tracheal intubation after 4 minutes of apnoea. Positive pressure ventilation commenced at Spo2 92%. Failure to obtain view of glottis with videolaryngoscope results in withdrawal from the study. Blood samples obtained from an arterial catheter immediately prior to commencing pre-oxygenation, after 90 and 180 seconds of pre-oxygenation, after each minute of apnoea until six minutes of apnoea, and every two minutes of apnoea thereafter, until Spo2 92%.
Active Comparator: Apnoeic oxygenation with high-flow nasal oxygen at 70 L/min (HFNO); 100% oxygen is administered via high-flow nasal cannulae at 70L/min from the onset of apnoea until four minutes of apnoea has completed.	Procedure: Apnoeic oxygenation; After 2mins 45 seconds of pre-oxygenation with high-flow nasal oxygen at Fio2 1.0 at 50L/min, anaesthesia is induced with 1-1.5mcg/kg remifentanil plus 2-3mg/kg propofol. Propofol (10mg/kg/hr) and remifentanil (0.15mcg/kg/min) infusions administered until study conclusion. At the onset of apnoea, 1mg/kg rocuronium administered. Jaw thrust performed. High-flow nasal oxygen adjusted to the randomised flow rate. Videolaryngoscopy after 1 minute of apnoea. Airway patency maintained. Tracheal intubation after 4 minutes of apnoea. Positive pressure ventilation commenced at Spo2 92%. Failure to obtain view of glottis with videolaryngoscope results in withdrawal from the study. Blood samples obtained from an arterial catheter immediately prior to commencing pre-oxygenation, after 90 and 180 seconds of pre-oxygenation, after each minute of apnoea until six minutes of apnoea, and every two minutes of apnoea thereafter, until Spo2 92%.
Active Comparator: Apnoeic oxygenation with high-flow nasal oxygen at 120 L/min (uHFNO); 100% oxygen is administered via high-flow nasal cannulae at 120L/min from the onset of apnoea until four minutes of apnoea has completed.	Procedure: Apnoeic oxygenation; After 2mins 45 seconds of pre-oxygenation with high-flow nasal oxygen at Fio2 1.0 at 50L/min, anaesthesia is induced with 1-1.5mcg/kg remifentanil plus 2-3mg/kg propofol. Propofol (10mg/kg/hr) and remifentanil (0.15mcg/kg/min) infusions administered until study conclusion. At the onset of apnoea, 1mg/kg rocuronium administered. Jaw thrust performed. High-flow nasal oxygen adjusted to the randomised flow rate. Videolaryngoscopy after 1 minute of apnoea. Airway patency maintained. Tracheal intubation after 4 minutes of apnoea. Positive pressure ventilation commenced at Spo2 92%. Failure to obtain view of glottis with videolaryngoscope results in withdrawal from the study. Blood samples obtained from an arterial catheter immediately prior to commencing pre-oxygenation, after 90 and 180 seconds of pre-oxygenation, after each minute of apnoea until six minutes of apnoea, and every two minutes of apnoea thereafter, until Spo2 92%.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Rise in arterial partial pressure of carbon dioxide	The rate of rise of the partial pressure of carbon dioxide between 60 seconds and 240 seconds of apnoea as measured by arterial blood gas analysis.	Between 1 and 4 minutes of apnoea

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Partial pressure of oxygen during apnoea	As measured by blood gas analysis	Following high-flow nasal oxygen administration
Time to oxygen desaturation	The time period from the onset of apnoea (determined by visual inspection) until an oxygen saturation of 92% is measured by pulse oximetry.	Immediately after the intervention
Change in carbon dioxide elevation before and after HFNO administration	As measured by blood gas analysis	Between 3 and 5 minutes of apnoea
Carbon dioxide elevation during the first minute of apnoea	As measured by blood gas analysis	Between 0 and 1 minute of apnoea
Change in acid-base status during apnoea	As measured by blood gas analysis	At 1 minute intervals during apnoea

Collaborators and Investigators

• Sponsor: University College Hospital Galway

Study record dates

Study Major Dates

• Study Start (Actual): November 22, 2021
• Primary Completion (Actual): May 25, 2022
• Study Completion (Actual): May 25, 2022

Study Registration Dates

• First Submitted: November 5, 2021
• First Submitted That Met QC Criteria: November 5, 2021
• First Posted (Actual): November 17, 2021

Study Record Updates

• Last Update Posted (Actual): July 11, 2022
• Last Update Submitted That Met QC Criteria: July 8, 2022
• Last Verified: July 1, 2022

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Respiratory Tract Diseases; Respiration Disorders; Signs and Symptoms, Respiratory; Apnea
• Other Study ID Numbers: CA2361

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: Yes
• IPD Plan Description: The sharing of anonymised patient-specific data that underlie results in any publication.
• IPD Sharing Time Frame: Post publication of results for up to fifteen years
• IPD Sharing Access Criteria: Investigator will consider requests to share patient-specific anonymised data in electronic format for the purpose of meta-analysis
• IPD Sharing Supporting Information Type: Study Protocol; Statistical Analysis Plan (SAP); Informed Consent Form (ICF); Clinical Study Report (CSR)

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No